A manner of scanning a beam in space is classified as a mechanical scan, an electronic scan or the like. At present, a common high gain antenna having a capability of scanning the beam in space is a parabolic antenna based on the mechanical scan or a phased-array antenna based on the electronic scan.
Since an orientation of the beam received (emitted) by the parabolic antenna is settled, it needs to rotate the parabolic antenna to fit the orientation of the beam when the beam is scanned in space. Therefore, the parabolic antenna has disadvantages of a great rotatory inertia, a slow speed and the like. Furthermore, since the parabolic antenna scans the beam mechanically, the parabolic antenna is bulky and has a complex structure. In consideration of limitation of the above disadvantages, the parabolic antenna is not suitable for a mobile platform, such as a vehicle, an aircraft, a satellite and the like.
Although overcoming the disadvantages caused by the parabolic antenna when the beam is scanned, and having advantages of a high beam scanning speed and a high phase varying speed, the phased-array antenna has a small application scope due to a complex structure.